It has been known to provide a grapple attachment for the buckets of loader tractors. Such grapplers typically comprise a plurality of fork-like teeth which swing down towards an open mouth of the bucket to either trap a load into or against a mouth of the bucket or to penetrate the load. For example, bales of hay may either be retained against a mouth of the bucket or in some prior art designs, the teeth of the bucket will penetrate the bale of hay.
In previous designs, the actuating mechanism for swinging the grapple down towards the bucket for engagement of a load typically had a fixed ratio between force and resistance arms. With such a mechanism, the pivot structure attaching the grapple to the bucket is subjected to large resisting forces requiring very large and heavy members and massive bearing systems.
In another method of actuating a grappling mechanism, a direct linkage is provided between a fixed point and the moveable grapple frame by use of an extendible power unit such as a hydraulic cylinder. The resultant force applied to the moveable grapple is quite small because the lever arm is very short and decreases as the grapple is closed.
In previous grapple designs, the grapple attachment to the loaders is either time-consuming or, if the attachment system is too simple, then large stresses develop at the attachment points which create product failure.